Dim configurationAppSettings As System.Configuration.AppSettingsReader = New _
   System.Configuration.AppSettingsReader
Dim connectionString As String = "Provider=Microsoft.Jet.OLEDB.4.0; Ole DB" & _
"Services=-4; Data Source=" & CType(configurationAppSettings.GetValue("pfad", _
GetType(System.String)), String) & "sap_debitor.mdb"
Dim dbConnection As System.Data.IDbConnection = New _
System.Data.OleDb.OleDbConnection(connectionString)
 
Dim queryString As String = "SELECT VPNR FROM VPNR WHERE VPNR = " & _
  Text_VPNR.Text & ""
Dim dbCommand As System.Data.IDbCommand = New System.Data.OleDb.OleDbCommand
 
Dim VPNR As Integer = 0
 
dbCommand.CommandText = queryString
dbCommand.Connection = dbConnection
dbConnection.Open()
Dim dataReader As System.Data.IDataReader = dbCommand.ExecuteReader()
Do While dataReader.Read
'ListBox1.Items.Add(dataReader.GetString(3))
VPNR = VPNR + 1
Loop
dataReader.Close()